Improvement in steam-boiler furnaces



E. F. GIRWHN.

Steam-Boiler Furnaces.

N0. 134,270. Patented Dec.24,1872.

EDGAR F. GRIFFIN, OF CHICAGO, ILLINOIS.

HWPRUVEWEENT IKN STEAWlBOILER FURNACES.

Specification forming part of Letters Patent No. 1134,@70, dated December 24, 1872.

, ing is a specification:

Nature of the Invention.

This invention relates to appliance for the more perfect combustion of the combustible vapors and gases liberated from the coal upon the gratebars of coal-burning furnaces, for the prevention of smoke and Waste of unconsumell combustibles.

When a charge of coal is put upon the grate-bars of a furnace and ignited, a process of destructive distillation takes place before the actual combustion, in which several gases and vapors are eliminated, principally carbureted hydrogen, bicar'oureted hydrogen, and carbon vapor, leaving a residue of coke or comparatively nearly pure carbon, Which latter is easily disposed of, as it Will remain upon the bars until consumed; not so, however7 with the gases above mentionedthe volatile products ofthe distillation. These, unless brought chemically in contact with a certain determined quantity of oxygen before they fall belovv a certain temperature, escape and Waste out of the chimney in a visible form, as with the precipitated carbon or soot and sooty vapor, or in an invisible form, as with the carbonio oxides and free hydrogen. One of tlie conditions prerequisite to combustion is, that the oxygen contained in the air must be brought atom by atom in chemical contact with the carbon or hydrogen with which it is to unite. It is not suflictent to merely rush a body of air rapidly through afurnace; in such case the atoms of oxygen at one point may come properly in contact, while at another point a cushion of interposed atoms of. nitrogen and oxygen may shield or prevent proper contact of the more distant atoms, and the result is that by the draft of this rapidlymoving body a large portion of heat is conveyed out of the stack, While the air has at the saine time (a portion of it) been of no value. The air which passes up through the gratebars through the burning coal is at once deprived of a greater portion of its oxygen,

which unites with the carbon, and is consequently no longer capable of furnishing a sufiicient supply for the combustion ofI the volatile portion of the fuel Which is rising from the coal. This volatile portion must therefore be supplied With oxygen from some other source than through the grate-bars, and in 'such manner as not to check the draft through the bars, nor to so accelerate it out of the stack as to prevent proper contact by rushing a body of unused air through above or aside from the heated gases and vapors.

Considering the premises as above stated, two important facts are presented, first, the volatile portion of the fuel must be supplied with oxygen sufficient for its combustion from some other source than through the grate; and, second, this supply of oxygen must be brought in chemical contact with said volatile fuel before it has fallen in temperature so much as to refuse combustion.

To the end of accomplishing these results, the present invention consists in projecting a series of jets of mingled heated steam and air from the front upper portion of the lire-place diagonally down to strike the incandescent coal at or near the extreme rear (a point near the boiler-fines or bridge-Wall) of the grate-bars. The mechanical effect of this blast of diagonal jets is to produce a rotary or reverberatory motion of the volatilized fuel (by which term is meant the several combustiblc gases and vapors rising from the ignited coal) and products ot' combustion ofthe coal on the bars, whereby the atoms of the combustibles are brought in contact with the incoming supply of oxygen and unite. The' mingled steam and air, already heated before entering, are still further heated in their passage through the lire-chamber, and are finally cast forcibly upon the incandescent coal, at which point they become so intensely heated that the gases not already freed and combined are at once set free to combine and burn, such as Will burn. VThe curtain of jets extending diagonally across the fire-chamber from front to rear offers no material obstruction to the necessary draft through the bars, nor to the proper escape of the products of combustion up the chimney, but retards the escape of the volatilized fuel, and keeps it Within the range of the required temperature until it has chemically combined with the oxygen thus. supplied necessary to its proper combustion.

In this invention particular importance is placed upon the location and direction of the jets aside from the material of which they are composed-air and steam heated together. The natural tendency of the draft is to avoid the upper front corner of the fire-chamber. The heat at this point is principally radiant, and the apparatus employed to castthe spray of j ets is thus spared the destructive effect of the intense heat to which it would be subject at any other part of the irechambcr. The diagonal direction of the jets from the front downward to near the extreme rear of the bars insures a thorough siftin g of all the. products before they reach theues, and also the beneficial reverberatory effect and it may be well to remark here, for sake of clearness, that this reverberation or returning of volatilized fuel toward the coal upon the bars is not done in the hope of burning it by casting it back upon the incandescent mass. This would be impossible, as it will not burn at all, however hot it may become, without union with its due proportion of oxygen 5 but it is donc with aview to superheat and detain it until it is made to meet its supply of oxygen, to keep it in a condition to burn when it finds the opportunity.

Description of the Drawing. nIn the accompanying drawing which forms a part of this specification, Figure 1 represents a central vert-ical section, from front to rear, of a steam-boiler furnace with this invention applied; and Fig. 2 represents a transverse Y vertical section through the hre-chamber look- 'the dre-box, above the fire-door, is placed the airchamber G, having access for air from outside. This chamber extends the entire width ofthe fire-box, and is perforated with a row of holes, g, along its length. Within this chamber is a central steam-pipe, H, furnished with a series of jet-tubes or nozzles, h, corresponding in number to the perforations g in the sides of the air-chamber G, and directed toward said perforations so as to cast a steamjet directly through each one in the direction of the dotted line marked Z. The natural draft of' the furnace tends to produce a partial vacuum at the particular point where the chamber G is placed, so thata constant supply of airis drawn into it from outside, and, standing momentarily there, becomes heated. A strong pressure of hot steam is admitted to the pipe H, which being heated, superheats and expands the steam, which, being blown from the nozzles h, will mingle with the hot air in the chamber G, and, by a percussive action, carry the hot air and steam combined through the perforations giuto the fire-box. The mingled current of steam and air thus combined and heated together, and divided into a sheet or curtain of jets, Z, strikes the incandescent coal at the point J at or near the rear of the grate-bars. The mass of volatilized fuel, carbureted hydrogen, oleant gas, and carbon vapor now lies all below the curtain Z, and, by the mechanical action thereof, is set in motion in the direction shown by the small arrows upon the drawing, having an open circle on the shaft, so that a new surface is constantly presented to the incoming oxygen-supply of thejet curtain, and none ofthe volatilized fuel can escape to the iiues without at least once passing into contact with said curtain, thus procuring chemical contact between the volatilized fuel and oxygen-supply while said fuel is at a high temperature, and insuring combustion.

The mingled hot steam and hot air fall forcibly upon the glowing coal at J, and a portion of the oxygen of the air still uncombined fans the coal at this point into an intense blow-pipe heat, into the focus of which the hot steam and nitrogen are projected, and at this high temperature the oxygen and hydrogen of the steam separate and burn, while the nitrogen serves as a bodyor medium to convey latent heat it may have absorbed to and disseminate 'it among the tlues.

The practical effect of the application of this apparatus to a furnace is to produce an absolutely smokeless combustion, with an increased heat, from a given amount of fuel.

I am aware that the general features and principles upon which my invention is based have been fully described and illustrated in several English patents; but I find in none of these provision for heating the air previous to its union with 4the steam; accordingly I disclaim all such.

'Claim'.

I claim as my invention- I l In combination with devices, substantially as herein described, for heating steam, and the delivery-pipe H, the air heating and distributing apparatus G placed within the combustion-chamber of a furnace, and varranged in the upper front corner of the same, and provided with perforations so disposed as to cast a curtain or vail of jets of mingled heated air and steam the entire breadth of the chamber downward in an oblique direction to the rear end of the grate-bars, as and for the purposes specified.

EDGAR F. GRIFFIN.

Witnesses:

J. W. MUNDAY, HEINR. F. BRUNs. 

